Had a problem with critters in the walls last year. He did pheromone rat trapping. Turned out to be a problem with an intercom power supply but Matt came out several times. Then he wrapped all stacks and sealed all roof returns so critters could not get in. This year, with their 3-year warranty in effect, I called when I noticed squirrels had chewed a hole at the bottom of one of my stacks. Matt came out within a few hours and took care of the problem. He also checked all vents and stacks that were still just fine. This company is outstanding and I highly recommend them.